brakes sticking

[diestech74]

Ok heres the back story in nov i had a caliper stick or i thought so i replaced it everything fine. then on monday the other side stuck coming out of the woods, so i thought i new i should have replaced them together and replaced it. today while in the woods the 1st side/ drivers side stuck again. so now the rest of story both times this week i was able to open the bleeder and release pressure and get home so the question i have is is thier a check valve in line or is the master going bad. im running a stock non power master but did do a chevy disk conversion and stock rear drums i think thats it what yall think

 

[75junebug]

I had the same thing happen to me on my conversion....I used Flebay calipers....1st one stuck and was changed out....I disassembled the piston from the caliper and found the inside was filled with rust and moisture. I had flushed the lines and bleed during install, but to no avail.....The passenger side has stuck a few times after the drivers side, but I havenot had a chance to install the new caliper yet....

 

[diestech74]

it seems that pressure is holding it closed best i know thier isnt a check valve in the caliper so is thier one up stream

 

[DirtDonk]

There might be. You'll have to physically check.
In the old days, most stock masters had them, but in later years for cost cutting reasons they no longer installed them in "most" master cylinders for our vehicles.

Pull the tube fitting off of the front disc reservoir (if stock, it's the rear of the master, large reservoir) and insert a poker/prober thingy into the hole to see if you feel springy resistance. If you do, then you'll have to pull the cone seat out of the port and remove the spring and seal. Put the cone back in, reinstall the brake line and re-bleed everything.

Before you do this however, even though it sounds like you know you got the disc retrofit right, take a peek over the top of your tire and make sure that you can look down on the caliper and see daylight between it and the steering knuckle. If there is anywhere that you don't see a gap, you need to grind more material.

Since the new caliper hoses are new too, they should not be at fault where old worn out ones can cause sticking. As well as a mushy pedal usually.

Since you don't have power assist, then it's not likely to be the linkage. But if this has been going on since the swap, and you replaced the master cylinder at the same time, just make sure that the pedal rod is not putting pressure on the master all the time.

Oh, and like junebug said, just because the calipers are new-ish, doesn't mean they're not defective. Happens way too often.

Good luck.

Paul

 

[diestech74]

thanks paul and bug the conversion was like 3 years ago and havent had trouble i didnt replace MC at the time and i did check for the cv in it las time it happened so ? is thier a ck valve in the factory h block/ balance meter that turns the light on i may just go ahead and put my hydro on but would light it working right before to cut down the trouble shooting

 

[DirtDonk]

Yes it would. Hate to have you chasing your tail all around during what should be a relatively simple install. But new parts just complicate things.
Unless of course, those new parts fix it!

No, unfortunately there is no check valve in the H-block either. Just a shuttle valve that moves between the two circuits and trips the switch when there is an imbalance.
I had originally thought the shuttle valve was capable of blocking off the low-pressure side (side with the leak) but apparently it does not shut off flow and only flips the switch for the light on the dash. Probably not a good idea to have something that purposely blocks the fluid from applying the brakes!

So, it comes down to a bad caliper (very possible), something clogging the lines (less likely, but not impossible), or something physically keeping pressure applied to the master cylinder's piston.
I suppose it's possible that a slightly rusty/corroded piston could stick in the master. Not returning to zero would keep pressure applied at the caliper.

Hmm, so I guess that new hydroboost with different master cylinder ain't sounding so bad after all.
Best to rule out everything else of course, but if it's the master, then a new one "should" fix things.

Good luck.

Paul

 

[diestech74]

thks dirt donk the part that has me leaning away from another caliper is thier is a physical pressure in the caliper and when you open the bleeder the caliper releases. that being said the pedal returns to top but does get very stiff or even hard at the top is it possible for fluid to get behind the master piston without leaking out?and why the one side or other problem

 

[DirtDonk]

Well there's the rub, right? If it's a problem upstream of the junction on the axle, it should work against both calipers. But perhaps, the driver's side being the short side, there's just enough to exert pressure there, but not the other side?
Never heard of such a thing, as it's supposed to be equal throughout the system, BUT, I run into a lot of things I've never heard of or experienced before. Once you find that, it becomes experience. But before that, it's a puzzlement.

A single bad hose maybe?
Debris in that hard line? Seems unlikely as most buildup of junk or rust would effect pressure both ways I would think. You'd see it also as a pull to one side when that caliper is not getting full pressure.
But here again, stranger things have happened.%)

Too bad you don't have someone you can swap calipers and other components with temporarily. Yeah, that's a lot of work to trace a problem, but at least you could eliminate pieces one by one without spending any money.

How about next time it does it, loosen the fittings one position further up?
When you run into a fitting that does not release the pressure, you might be on to something. Even to the point of loosening the nuts that hold the master to the firewall, to let it pull forward off the pedal. It's always possible that the pedal is putting pressure on the system, but the driver's side is more sensitive to it.
Also, while still working with components down on the axle, don't forget to open up the bleeder on the opposite caliper, to see if that also releases the pressure on the driver's side.
Maybe the reason it's only one side is that the passenger side is a little sticky and takes more pressure to hold against the rotor.

Good luck.

Paul